In general, automobile cars and vessels generate power necessary to be driven by using a fossil fuel such as gasoline or diesel oils, but generate exhaust gas such as carbon monoxides and nitrogen oxides that are harmful to the human body, according to an incomplete combustion of the fuels in view of the structural nature. Accordingly, the automobile cars and vessels include a variety of devices in the respective components of the automobile cars and vessels that generate hazard exhaust gas due to incomplete combustion of the fuel, such as a combustion chamber that performs combustion of fuels such as gasoline and diesel oils, an air intake system that performs a mixture of air and fuel, and an exhaust gas system that discharges exhaust gas, to thereby suppress an amount of exhaust gas at maximum.
Thus, a catalytic converter is attached and used in between an exhaust pipe through which exhaust gas is discharged to the outside, in order to remove harmful ingredients from the exhaust gas. The catalytic converter uses an oxidation catalyst that oxides carbon monoxide (CO) and hydrocarbons (HC) from exhaust gas to be converted into carbon dioxide (CO2) and water (H2O), and a reduction catalyst that reduces nitrogen compounds (NOx) into nitrogen (N2). In addition, in order to meet requirements such as temperature required for reaction and residence time of exhaust gas, an effective area of the catalytic converter becomes large, and furthermore a catalyst support on the surface of which particle-shaped catalysts are attached is mounted in a housing.
Meanwhile, the catalyst support has a honeycomb structure consisting of rectangular or hexagonal cells, on which a catalyst is coated to cause an oxidation and reduction reaction of harmful components from among exhaust gas.
Therefore, the exhaust gas entering the inside of the housing via the exhaust pipe performs a catalytic reaction with the catalyst coated on the catalyst support and then is discharged to an exit unit.
An example of a catalyst support of a honeycomb structure is disclosed in Korean Patent Registration No. 527970, and will be described with reference to FIGS. 1 and 2.
Catalyst supports 1a and 1b are formed of cells 4a and 4b respectively having a rectangular cell structure shown in FIG. 1 and a hexagonal cell structure shown in FIG. 2. Each cell 4a or 4b forms a penetration hole 3a or 3b, respectively. A catalyst coating layer such as alumina (for example, Al2O3, etc.) including precious metals is coated between the cell 4a and a cell passage barrier 2a and between the cell 4b and a cell passage barrier 2b. The catalyst supports 1a and 1b perform an oxidation and reduction reaction of exhaust gas by the catalyst coated on the catalyst coating layer, respectively, to thus exert a function of removing harmful components from among exhaust gas.
A catalytic support for automobile cars is formed of a ceramic integrated cell structure having a circular cell structure, to thus obtain a uniform distribution of a coating layer and a small vertical height between cell lines, and to thereby increase a cell density. By doing so, a sufficient contact reaction condition between the catalyst support and the exhaust gas is guaranteed, to thus improve an entire exhaust gas purification efficiency of the catalytic converter.
However, since the catalytic support for automobile cars is manufactured by an extrusion process that feeds a ceramic raw material to an extruder and pushing out the extruded ceramic raw material from a mold, so as to be converted into a continuum formed of a honeycomb shaped cross-section, it is difficult to apply the catalytic support to places where a large capacity catalytic reactor is needed for large vessels or plants using a number of large engines.
In addition, a diesel exhaust gas pollution reduction device that is obtained by extrusion molding a high hardness material such as a diesel particulate filter (DPF) for use in diesel engines, for example, silicon carbide (SiC) is expensive, suffers from a short-lived extrusion mold, and causes a number of molds to be retained depending on types of mass produced products.
Moreover, the catalyst support disclosed in the Korean Patent Registration No. 527,970 has a cylindrical external support regardless of the cell structure. Thus, a number of the catalyst supports may not be easily cross-assembled for the purpose of integrating them into a large-capacity assembly structure.
According to the conventional art described above, attempts were made by stacking a number of cylindrical unit catalyst support blocks formed of a ceramic structure in order to manufacture a large-capacity catalyst support, but as described above, it was difficult to manufacture a large-capacity catalyst support.
Meanwhile, in the case that catalyst supports are made of metal, it is easy to manufacture catalyst supports of 30 cm or less in diameter but is difficult to manufacture catalyst supports of more than 30 cm in diameter.
In particular, the International Maritime Organization (IMO) adopted the International Convention on the Prevention of Marine Pollution from Ships (MARPOL), in 1973. Here, a marine engine exhaust nitrogen oxide regulation program mentions that exhausts nitrogen oxides (Nox) decrease by 20% compared to a 1973-based current amount in Tier II starting from 2011, and decrease by 80% in Tier III starting from 2016. For reference, the International Maritime Organization (IMO) is one of the specialized agencies of the United Nations in order to internationally unify the ship's routes, traffic rules, port facilities, and so on. As a result, the large vessel industry using large engines has been conducting active researches on a large-capacity catalytic converter for purifying nitrogen oxides contained in the exhaust gas.
Therefore, the catalytic converter is required to have a structure of being manufactured and provided from a small-capacity structure from a large-capacity structure so as to process a large amount of exhaust gas in large vessels or plants employing a number of large-scale internal combustion engines, or large food processing devices.